Bob,
Have you seen the description of "Full-Text Searching and the Burrows-Wheeler Transform" in the December, 2003 issue of Dr. Dobb's Journal (you were thinking of subscribing to it a year or so ago). It's fairly easy to read (I understood every third word, or so), and covers searching in some depth. It also mentions compression for added efficiency. Unfortunately, I got lost when the author (Kendall Willets) discussed "The Location Problem" which is probably the most critical issue.
In any case, since you're currently working in that area, it seemed worthwhile to mention it to you.
Fred